Community Structure & Dynamics

Question 1

climax community

Answer 1

stable, final community that develops from ecological succession

Question 2

keystone species

Answer 2

species w/ exceptionally great impact on other species in its ecosystem relative to its abundance
- removal/addition could change community structure

(ie) sea stars control mussel populations

Question 3

disturbance

Answer 3

any strong, short-lived disruption to a community that changes distribution of living and/or nonliving resources
- usually occurs w/ predictable frequency (how often) & severity (how massive)

(ie) tree falling, forest fire, disease epidemics, short-term explosion in # of herbivores

Question 4

disturbance regime

Answer 4

characteristic disturbances that affect a given ecological community

• includes how often it occurs
• includes what happens when it occurs

Question 5

succession

Answer 5

gradual habitat recovery after environmental disturbance

• usually by a series of species
• species traits & interactions makes succession predictable
• history & chance contribute a degree of unpredictability to succession

Question 6

primary sucession

Answer 6

gradual habitat recovery after disturbance removes all soil & orgs
- bare rock or gravel

(ie) glaciers, floods, volcanic eruptions & landslides initiate PS

COMPLETE RESET

Question 7

secondary succession

Answer 7

gradual habitat recovery after disturbance removes some or all previous orgs but leave soil intact
- primary & secondary succession

(ie) fire & logging initiate SS

DELETE

Question 8

pioneering species

Answer 8

species that appear first in recently disturbed areas

Question 9

weed

Answer 9

any plant that adapts for growth in disturbed soils

- thrive @ start of SS

Question 10

facilitation

Answer 10

early arriving species make conditions MORE favorable for later arriving speices

(ie) plants provide shade & nutrients that become organic matter

Question 11

tolerance

Answer 11

early arriving species DO NOT EFFECT probability that subsequent species will become established

Question 12

inhibition

Answer 12

early arriving species make conditions LESS favorable for establishment of later arriving species

inhibit = stop/prevent

Question 13

attributes of community structure

Answer 13

(1) total # of species
(2) relative abundance of those species
(3) sum of interactions among all species
(4) physical attributes of community - biotic/abiotic

Question 14

Fredrick Clements biological community view

Answer 14

biological communities = stable, orderly & predictable

• develop same community of species due to coevolution
• extensive interactions
• begin formation of climax community
• determined by climate & biotic factors

Question 15

Henry Gleason biological community view

Answer 15

communities are not stable or predictable

• each should develop different communities
• determined by chance

Question 16

reality of biological community views

Answer 16

balance btwn both views

- leans more to Gleason